Which is better RVCE or VIT

How to create high frequency white noise in a circuit

The answer depends somewhat on the bandwidth over which the noise spectrum needs to be flat. If this bandwidth is in the audio range or up to a few MHz, consider a digital approach that uses a so-called “M-sequence generator” (which can be googled) that drives a digital-to-analog converter, followed by a suitable low-pass filter. This approach can be very useful for bandwidths up into the multiple MHz range. A virtue of the M-sequence approach is that its "statistics" are (so to speak) completely stable and predictable.
For much higher frequencies, an alternative approach is to start with a reverse biased diode of some type that produces “high quality” noise in this mode of operation, followed by a broadband amplifier when more power is needed.
An amplifier with a reactance load as an input termination will also, in principle, output "white" noise across the amplifier's operating band, but the large amount of gain associated with this approach makes it more susceptible to various sources of spectrum pollution, e.g. B. Recording of television channels in the area, etc. In some applications, the input dummy load can be operated at elevated temperature to increase the output noise level.

Maxim Integrated has a white paper that describes how:

Construction of an inexpensive white noise generator